QUESTION OVERHEATING

I just bought a 1997 Isuzu Rodeo V6 4x4 and I have a problem with it over heating. I changed the thermostat and that didn't do anything. The radiator isn't boiling over when at idle and the radiator cap is off, just a couple air bubbles or so and there is no water coming out of the tail pipe or the head and no water in the oil. The radiator is also hot the whole way across so that is almost out of the picture. I can also rule out the fan or the fan clutch because the fan turns on just fine just squeals a little bit at first when you start the truck. I did notice however that there is low oil pressure and I am not getting any heat inside the vehicle at all. I am stumped as to what the problem might be. If you have any ideas and could help me I would really appreciate it.

The car overheats after about 5-10 minutes of driving it depending on the temperature outside I assume. The only reason that I have to add water to the radiator is because when I pull over to let it cool down it might need a little more water but other than that I don't let it get hot enough to the point where it starts to have steam rolling out from under the hood. I really don't have any loss of coolant. It doesn't matter how fast you drive it just overheats.

Since the temp is getting up so fast, the possibility is more likely to be insufficient flow of coolant around the cooling system. You mentioned the heater not working, so I would suspect a faulty water pump.

Do this simple test but be careful as the engine and its components would be hot.
After running engine for 2 or 3 mins, feel the lower radiator hose to see if it is hot or cold. Needs to be done with engine running.
Upper hose would definitely be hot.

If hose remains colder than the upper hose by a vast difference and temp gauge shows HOT, you need to check out the water pump. Its turbines could be damaged.

I've already done that and both hoses are hot. The only thing that I could come up with is that it is air locked somewhere inside the block and the air pocket is preventing it from moving throughout the block allowing it to cool. Other than that I'm stumped. I was told that there was a new water pump put in it but I'm not sure if that is the truth; I sort of got screwed over on the deal. I have msn messenger if you want to talk more in detail on there. My screen name thing is bls5141@live. Com I appreciate any help you can give me. Thank you!

If there is air trapped, it should show as coolant losses when cold. The radiator would show low level.

It is not easy to test the water flow and the easiest way is to temporarily remove the thermostat and run the engine with radiator cap off. Watch the coolant movement from the cap neck and if the speed is slow or none moving, you need to check the water pump again.

If the flow is fast, reinstall the radiator cap and test drive to see if the temp goes up. If it does not go up, replace the thermostat, it could be faulty, new parts do fail too.